CN107893772B

CN107893772B - Centrifugal fuel cell air compressor with energy recovery function

Info

Publication number: CN107893772B
Application number: CN201710928394.0A
Authority: CN
Inventors: 王凯; 钱星; 倪永成; 居钰生; 夏少华; 易正根; 徐秀华; 陈雷雷; 许洪瑜
Original assignee: FAW Group Corp
Current assignee: FAW Group Corp
Priority date: 2017-10-09
Filing date: 2017-10-09
Publication date: 2020-05-22
Anticipated expiration: 2037-10-09
Also published as: CN107893772A

Abstract

The invention discloses a centrifugal fuel cell air compressor with an energy recovery function, which comprises a motor, a compressor shell, an expansion shell and an air inlet cover, wherein the compressor shell is arranged on the motor; a compressor impeller and an expander impeller are mounted at one end of a motor shaft and are respectively surrounded by a compressor shell and an expander shell to form a compressed air flow passage and an expander flow passage, and a bypass valve is arranged between the compressed air flow passage and the expander flow passage. The invention adopts the centrifugal air compressor and the turbine expander to recover the energy of the discharge of the electric pile, thereby improving the efficiency of the system. And the scheme of the integrated design of the air compressor and the expansion machine backrest is adopted, so that the whole system is compact, the power-weight ratio is high, and the efficiency is high. The occurrence of surging in the case of small air flow for supplying the stack is avoided by the control of the bypass valve, and the energy of the bypassed air can also be recovered by the expander.

Description

Centrifugal fuel cell air compressor with energy recovery function

Technical Field

The invention belongs to the technical field of fuel cell engines, and particularly relates to a centrifugal fuel cell air compressor with an energy recovery function.

Background

Supercharging of the air consumed is an essential means for a fuel cell engine. On the one hand, the power density of the fuel cell can be increased, and on the other hand, the oxygen partial pressure influences the gibbs free energy in the chemical reaction, thereby influencing the efficiency limit of the fuel cell. At present, an air pressurization system for a fuel cell engine generally adopts a double-screw type, roots type or centrifugal air compressor as a core compression pump.

Air compressors for fuel cells are mainly classified into two types, one type being positive displacement air compressors, and the other type being commonly used as twin-screw type and roots type air compressors. Its advantages are simple structure, easy control, obvious defects, high volume and weight and low efficiency. The other type is a centrifugal air compressor which is characterized by small volume, light weight and high efficiency, but the control is relatively complex. Centrifugal air compressors, while being highly efficient, also have their inherent surge drawbacks. When the operating condition point of the centrifugal air compressor moves to a certain degree in the direction of small flow, unstable flow condition, namely surge, can occur, pipeline pressure oscillation is caused, flow changes rapidly, efficiency is reduced, and the impeller of the air compressor can be damaged in serious cases. Surging is the working condition that centrifugal air compressor should be avoided as much as possible in operation. Since fuel cells require a small flow rate and high pressure of air at a small load in order to improve reaction efficiency, appropriate measures must be taken to avoid surge.

Relevant research shows that the consumed power of the fuel cell air pressure pump is about 20-30% of the output power, and is a large energy consumer in a fuel cell auxiliary system. Increasing the efficiency of the air compressor can improve the efficiency of the entire fuel cell system.

Disclosure of Invention

The invention aims to provide a centrifugal fuel cell air compressor with an energy recovery function, which aims to overcome the inherent surge defect of a centrifugal air compressor by improving the overall efficiency of a fuel cell system aiming at the defects of the existing fuel cell air compressor.

In order to achieve the purpose, the invention adopts the following technical scheme:

a centrifugal fuel cell air compressor with an energy recovery function comprises a motor, a compressor shell, an expansion shell and an air inlet cover; the method is characterized in that: the compressor impeller and the expander impeller are respectively surrounded by the compressor shell and the expander shell to form a compressed air flow passage and an expander flow passage, and a bypass valve is arranged between the compressed air flow passage and the expander flow passage.

It is further characterized in that: the compressor impeller and the expander impeller are integrated back to form a composite impeller.

Further: the edge of the composite impeller and the inner edge of the expansion casing form a non-contact labyrinth seal.

Preferably: the bypass valve is a butterfly valve, and the bypass opening degree can be adjusted by changing the angle of the bypass valve through a bypass valve actuator.

The motor is arranged in a motor shell, one end of the motor shell is fixedly connected with the air inlet cover, and the other end of the motor shell is fixedly connected with the compressor shell; an air flow channel is arranged between the motor and the inner wall of the motor shell.

And heat radiating fins are arranged outside the shell of the motor and radiate the motor through air inflow.

And the end cover of the motor is provided with a vent hole, and the inlet air flows into the motor through the vent hole to cool the motor rotor and the bearing.

And two ends of the motor shaft are supported by high-speed rolling bearings.

The invention adopts a high-efficiency centrifugal air compressor as a compression core component, and simultaneously, the high-efficiency centrifugal air compressor is matched with a turbo-expander to recover the energy of the discharged gas of the electric pile, so that the efficiency of the whole system is further improved. And the scheme of the integrated design of the air compressor and the expansion machine backrest is adopted, so that the whole system is compact, the power-weight ratio is high, and the efficiency is high.

The control of the bypass valve ensures that the flow of the compressor is not too small under the condition that the flow of the air for supplying the electric pile is small so as to avoid surging, and the energy of the bypassed air can be recovered through the expander.

The motor is arranged in the air inlet channel, and air flow in the air inlet channel flows through the motor and the bearing, so that the working temperature of the motor and the bearing is reduced, and the reliability of the system and the motor is improved.

Drawings

FIG. 1 is a schematic view of the present invention.

FIG. 2 is a schematic view of the internal structure of the present invention.

FIG. 3 is a schematic view of a rotor assembly.

Fig. 4a is a schematic structural view of a composite impeller.

Fig. 4b is a schematic view of a composite impeller sealing structure.

Fig. 5a and 5b are schematic diagrams of the working state of the bypass valve.

Fig. 6 is a schematic view of the internal structure of the expander.

Fig. 7 is a schematic view of the internal structure of the motor.

Detailed Description

As shown in fig. 1 and 2, the centrifugal fuel cell air compressor with energy recovery function comprises a motor casing 9, a rotor assembly, a compressor casing 11, an expansion casing 14 and an air inlet cover 1. The motor part comprises a motor casing 9, a stator 8 and a motor cover 2, and the motor cover 2 is fixed on the motor casing 9 through a motor cover bolt 4.

The air inlet cover 1 is connected with a motor shell 9 through an air inlet cover bolt 5, the motor shell 9 is connected with a compressor shell 11 through a motor shell bolt 10, and an expansion shell 14 is fixed on the compressor shell 11 through an expansion shell bolt 13.

As shown in fig. 2 and 3, the rotor assembly is formed by locking the bearing 3, the motor rotor 7, the composite impeller 12 and the bearing 15 on the rotating shaft 6 through the locking nut 16. The bearings at two ends of the rotating shaft 6 adopt high-speed rolling bearings, lubricating oil is not needed, oil separation measures are not needed, and meanwhile, the rolling bearings can bear certain axial force and play a role of a thrust mechanism.

As shown in fig. 4a and 4b, the composite impeller 12 has a compressor blade 122 and an expander blade 123 integrated on the same impeller, and the two blades are arranged back to back, so that the structure is compact. The composite impeller 12 edge 121 and the corresponding expander casing 14 inner edge 141 form a labyrinth seal to prevent the compressed air and stack exhaust from escaping. The wall 142 of the expander casing 14 and the wall 111 of the compressor casing 11 together form a compressed air flow path.

As shown in fig. 5a and 5b, the inner bypass valve structure has a bypass hole formed in an inner wall surface of the expander casing 14, the bypass hole connects the compressed air flow path and the expander flow path, a bypass valve 18 is installed in the bypass hole, and the bypass valve 18 is controlled by a bypass valve controller 17. The bypass valve 18 is a butterfly valve, and the bypass airflow can be adjusted by changing the angle of the bypass valve 18. Fig. 5a shows the bypass valve closed state and fig. 5b shows the bypass valve partially open state.

As shown in fig. 6, a bearing support 144 of the left end bearing 15 is provided at the outlet of the expansion casing 14 for supporting the rotor assembly, and the bearing support 144 is fixed by the column 143 while leaving a flow passage 145 for gas to flow.

As shown in fig. 7, the motor housing 9 has a stator housing 91 for mounting the motor stator 8, and the stator housing 91 is fixed to a motor housing 94 by a stator housing holder 93. An air flow passage 95 is formed between the stator case 91 and the motor housing 94 for circulation of intake air, and at the same time, heat radiating fins 92 are provided outside the stator case 91 for enhancing heat radiation. The motor cover 2 is provided with ventilation openings 21 which, by introducing a head-on intake air flow, cool the bearing 3 on the one hand and the motor rotor 7 and the motor stator 8 inside the motor on the other hand.

The working principle of the invention is as follows: when the electric pile needs to work, the motor is started to drive the composite impeller 12 to rotate, air is sucked under the drive of the compressor impeller 122, and airflow flows through the motor to play a cooling role. Air is compressed and then input into a fuel cell stack, gas with certain temperature and pressure after reaction is discharged out of the stack and enters an expander to push an impeller 123 of the expander, and partial energy is recovered, so that the power of a driving motor is reduced, and the overall efficiency of the stack is improved. When the electric pile is in a high-power working condition, the bypass valve 18 is closed so as to fully utilize the flow of the compressor. When the electric pile is in a low-power working condition, the air requirement of the electric pile is low, but a certain pressure needs to be maintained. However, the centrifugal compressor has a "surge" problem under a low flow condition, so that the flow of air flowing through the compressor impeller 122 is maintained, and a bypass valve 18 is opened to bypass a part of air directly, so that the flow entering the pile is reduced, and meanwhile, the bypassed air enters the expander to recover energy directly, so that no waste is caused.

Claims

1. A centrifugal fuel cell air compressor with an energy recovery function comprises a motor, a compressor shell, an expansion shell and an air inlet cover; the method is characterized in that: a compressor impeller and an expander impeller are mounted at one end of a motor shaft, the compressor impeller and the expander impeller are respectively surrounded by a compressor shell and an expander shell to form a compressed air flow passage and an expander flow passage, and a bypass valve is arranged between the compressed air flow passage and the expander flow passage;

the compressor impeller and the expander impeller are integrated back to form an integrated composite impeller; the bypass valve is a butterfly valve, and the bypass opening degree can be adjusted by changing the angle of the bypass valve through a bypass valve actuator.

2. The centrifugal fuel cell air compressor with energy recovery function according to claim 1, characterized in that: the edge of the composite impeller and the inner edge of the expansion casing form a non-contact labyrinth seal.

3. The centrifugal fuel cell air compressor with energy recovery function according to claim 1, characterized in that: the motor is arranged in a motor shell, one end of the motor shell is fixedly connected with the air inlet cover, and the other end of the motor shell is fixedly connected with the compressor shell; an air flow channel is arranged between the motor and the inner wall of the motor shell.

4. The centrifugal fuel cell air compressor with energy recovery function according to claim 1, characterized in that: and heat radiating fins are arranged outside the shell of the motor and radiate the motor through air inflow.

5. The centrifugal fuel cell air compressor with energy recovery function according to claim 1, characterized in that: and the end cover of the motor is provided with a vent hole, and the inlet air flows into the motor through the vent hole to cool the motor rotor and the bearing.

6. The centrifugal fuel cell air compressor with energy recovery function according to claim 1, characterized in that: and two ends of the motor shaft are supported by high-speed rolling bearings.